Perfluorodioxane derivatives known in the art include perfluoroethyl-1,4-dioxane and perfluoropropyl-1,4-dioxane of the following formulae as reported in WO 84/02909 by ICI. ##STR1## These compounds are stable fluids useful as heat pump media, solvents and heat transfer media.
These compounds, however, suffer from a serious problem in their manufacture. More particularly, the perfluoroethyl derivatives are synthesized by a process as shown by the following scheme. ##STR2##
This process involves high-temperature radical reaction in an autoclave and fluorination reaction with CoF.sub.3 at very high temperatures. The reaction can be commercially practiced always with difficulty with respect to safety management, reaction control, and synthesis equipment cost. Especially the fluorinating agent CoF.sub.3 must be prepared using F.sub.2 gas, which requires extremely careful operation